C02-Wireless_Transmission - Mobile Communications Chapter 2...

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Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS05 2.1 Mobile Communications Chapter 2: Wireless Transmission Frequencies Signals Antenna Signal propagation Multiplexing Spread spectrum Modulation Cellular systems
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Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS05 2.2 Frequencies for communication coax cable VLF = Very Low Frequency UHF = Ultra High Frequency LF = Low Frequency SHF = Super High Frequency MF = Medium Frequency EHF = Extra High Frequency HF = High Frequency UV = Ultraviolet Light VHF = Very High Frequency Frequency and wave length: λ = c/f wave length λ , speed of light c 3x10 8 m/s, frequency f 1 Mm 300 Hz 10 km 30 kHz 100 m 3 MHz 1 m 300 MHz 10 mm 30 GHz 100 µ m 3 THz 1 µ m 300 THz visible light optical transmission twisted pair VLF LF MF HF VHF UHF SHF EHF infrared UV
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Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS05 2.3 Frequencies for mobile communication VHF-/UHF-ranges for mobile radio simple, small antenna for cars deterministic propagation characteristics, reliable connections SHF and higher for directed radio links, satellite communication small antenna, beam forming large bandwidth available Wireless LANs use frequencies in UHF to SHF range some systems planned up to EHF limitations due to absorption by water and oxygen molecules (resonance frequencies) z weather dependent fading, signal loss caused by heavy rainfall etc.
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Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS05 2.4 Frequencies and regulations ITU-R holds auctions for new frequencies, manages frequency bands worldwide (WRC, World Radio Conferences) Europe USA Japan Cellular Phones GSM 450-457, 479- 486/460-467,489- 496, 890-915/935- 960, 1710-1785/1805- 1880 UMTS (FDD) 1920- 1980, 2110-2190 UMTS (TDD) 1900- 1920, 2020-2025 AMPS , TDMA , CDMA 824-849, 869-894 TDMA , CDMA , GSM 1850-1910, 1930-1990 PDC 810-826, 940-956, 1429-1465, 1477-1513 Cordless Phones CT1+ 885-887, 930- 932 CT2 864-868 DECT 1880-1900 PACS 1850-1910, 1930- 1990 PACS-UB 1910-1930 PHS 1895-1918 JCT 254-380 Wireless LANs IEEE 802.11 2400-2483 HIPERLAN 2 5150-5350, 5470- 5725 902-928 IEEE 802.11 2400-2483 5150-5350, 5725-5825 IEEE 802.11 2471-2497 5150-5250 Others RF-Control 27, 128, 418, 433, 868 RF-Control 315, 915 RF-Control 426, 868
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Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS05 2.5 Signals I physical representation of data function of time and location signal parameters: parameters representing the value of data classification continuous time/discrete time continuous values/discrete values analog signal = continuous time and continuous values digital signal = discrete time and discrete values signal parameters of periodic signals: period T, frequency f=1/T, amplitude A, phase shift ϕ sine wave as special periodic signal for a carrier: s(t) = A t sin(2 π f t t + ϕ t )
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